A library to add properties to components

[Scott Ferguson]

This libary allows the user to associate new properties with a component.

It contains:

• a shared global variable NewProperties -- container for a lookup in pairs to hold component keys and their associated property keys and values
• NewComponent procedure - creates an entry in the pairs list for the specified component instance and it's list of properties
• NewProperty procedure - creates an entry in the pairs list for the specified component's property and it's initial value
• getPropertyValue procedure with result - reads the current component's property value
• setPropertyValue procedure - used to update the component's property value

Download the attached aia project file which contains this library and upload it to App Inventor.

When the project opens, go to the Blocks Viewer, right-click on the desktop and choose Copy All Blocks to Backpack:

Open or create the project you wish to add the blocks to and drag out the blocks you need from Backpack.

The following Canvas, Ball and Imagesprite examples show how to use the blocks:

                                   (Click on the Images below to zoom in)

Create a global variable to hold the new properties:

Create entries in the master list to hold each component instance and it's list of properties:

Create properties for each component instance and set their initial values:

Read a value from a component's new property:

Set or replace a value in a component's new property:

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sf